What is the typical purpose of an antibiotic spacer in a two-stage revision for infected arthroplasty?

• A. To deliver high local antibiotic concentrations while maintaining joint space and some soft tissue tension for later reimplantation.
• B. To deliver systemic antibiotics and immobilize the limb completely.
• C. To replace the prosthesis permanently.
• D. To fill the joint with sterile saline.

Answer: (A)

The main idea is that an antibiotic spacer in a two-stage revision is used to treat infection locally while preserving the environment for a future replacement. Placing the spacer delivers high concentrations of antibiotics directly to the joint, which helps eradicate bacteria more effectively than systemic antibiotics alone. At the same time, the spacer occupies the joint space and maintains some soft tissue tension, preserving space and preventing collapse or contractures so that a new implant can be reimplanted more easily in the second stage. It may be an articulating spacer to allow some movement, which can further help with soft tissue viability and function.

This isn’t about delivering systemic antibiotics by itself, and it doesn’t represent a permanent replacement of the prosthesis. It also isn’t simply filling the joint with sterile saline, which would fail to provide antibiotic therapy or maintain the necessary tissue planes for later reimplantation.